The present invention relates to reclining and fold-flat mechanisms for the passenger seats in a vehicle. More specifically the invention relates to a mechanism that allows a seat to be folded flat from any recline angle and to maintain or remember the previously set recline angle when the seat is returned to its upright position.
Many seat reclining mechanisms are known and used in the automotive industry. In some applications, a fold-flat feature is provided that allows the seat back to be folded to a position substantially parallel to the seat bottom. This is particularly useful for carrying cargo and is commonly found in vans and sport utility vehicles. Some amount of fold over is also required in two door vehicles for access to the rear seat or rear compartment area. In addition, it is desirable to provide some degree of recline adjustment, at least for front seat occupants; however, some vans and SUV""s also include this feature in the rear seats.
Current fold-flat systems are of two general types. One, the dedicated fold-flat mechanism, provides no recline function. The other is the rotary recliner with extended forward travel to a fold-flat position. The dedicated fold-flat mechanism is typically used in second or third row seating where the lack of a recline feature is less detrimental. Typical rotary recliner systems reposition the seat back to its forwardmost recline position during the fold-flat process thus requiring the recline angle of the seat back to be readjusted after the seat back is returned to an upright position. This shortcoming is particularly evident in those systems that combine the recline and fold-flat operations in a single actuation means. In addition, these systems also tend to require substantial manipulation to fold the seat back or restore the seat back to an upright position. As a result, systems have been developed that separate the seat recline feature from the fold-flat feature. These devices separate folding from the normal adjustments of the seat back so that the seat back does not lose its predetermined angle of inclination. Optimally, the pivot point for folding the seat back flat is higher than the pivot point for reclining the seat back.
One example is shown by patent U.S. Pat. No. 5,806,932, which is owned by the assignee of the present invention. The ""932 patent relies upon a memory latch to establish the angle of inclination of the seat back. The memory latch is allowed to pivot when the seat is operated in its dump mode. In this dump position, the seat back is in its forward-most position for ingress/egress to the back seat or rear compartment. When the dumping has been completed, the latch is restored to its locked position to thereby re-establish the seat back at its user set angle. While the system of the ""932 patent provides significant benefits over the prior adjustment mechanisms, there remains a need for improvements to seat adjustment and fold-flat mechanisms. For instance, most prior adjustment and fold-flat mechanisms rely upon relatively bulky stamped metal components that can be expensive and difficult to assemble.
There is therefore a need for a reclining mechanism with a memory feature that allows the seat back to fold flat when folded, while preserving the recline angle of the seat back. In addition, there is a need for such a system that is easy to operate, lightweight, compact, and that can be manufactured at a reasonable cost.
In order to address the needs left unfulfilled by prior devices, the present invention contemplates a fold-flat recliner mechanism for use in a vehicle seat that allows the seat back to be folded to a flat position relative to the lower seat cushion.
In one embodiment, the mechanism includes an upper plate attached to the seat back frame and a lower member pivotably attached to the seat cushion frame. The upper plate is pivotably connected to the lower member. A pair of links also pivotably interconnect the lower member and the seat cushion frame forming a parallelogram linkage that maintains a fixed and substantially parallel relationship between the seat back and lower seat cushion when the seat back is in a fold-flat position. The upper plate includes a stop pin that engages a stop area on one of the parallelogram links to stop the seat back in the substantially parallel position when the seat back is folded.
The mechanism also includes latch means to control folding of the seat back. Here, the lower member can include a slot within which the pin on the upper plate travels. A pawl retains the pin against one end of the slot when the seat back is in an upright position. A release lever is biased against the pawl to prevent folding of the seat back.
In another embodiment of the invention, the lower member is an assembly including left and right plates connectable to each other and pivotably connected to the seat cushion frame. An upper plate attached to the seat back is pivotably connected between the two lower plates. Links on either side of the assembly complete the formation of a parallelogram that maintains a fixed and substantially parallel relationship between the seat back and seat cushions when the seat back is folded.
In this embodiment, a link pin passes through an arcuate slot in the lower plates connecting link members on the right and left sides of the lower assembly. The slot limits the reclining range of the seat back. The link pin also operates as a stop when the seat back is folded by engaging a stop notch at the end of the upper plate. A fastener connecting the left and right plates also acts as a stop when the seat back is raised to an upright position. Folding of the seat back is controlled by a release lever mounted between the lower pates. The release lever is biased by a spring in a position engaging the lower end of the upper plate to inhibit folding of the seat back. Raising the release lever allows the seat back to be folded.
In both embodiments, the mechanism xe2x80x9cremembersxe2x80x9d the last set recline angle and returns to that recline angle when the seat back is raised from the fold-flat position. Also, in both embodiments, a separate assembly for adjusting the recline angle attaches to the lower end of the lower member.
It is an object of the invention to provide an easy to use reclining mechanism that allows the seat back to fold flat relative to the seat cushion, while preserving the recline angle of the seat back. The ability to fold the seat back to a flat or substantially parallel relationship should be maintained throughout the range of reclining positions for the seat back.
This and other objects, advantages and features are accomplished according to the devices, assemblies and methods of the present invention.